With the growth of the internet, more mobile devices and the increased amount of traffic, there are some new methods such as css3 and HTML5 which can be used to minimise the amount of requests sent by the users' browser.

This, in turn, reduces the amount of information needed to be sent over both phone lines and mobile networks and increases the amount of work done by the users' computer.

All this adds up to less traffic to and from one user, less data usage for mobiles...